WP Ajax search (ACF included)

functions.php

<?php 
/* Wordpress Custom Search by title, ACF, post_meta */

// Wordpress ?s= redirect to /search/
function wpa_search_redirect() {
    global $wp_rewrite;
    if (!isset($wp_rewrite) || !is_object($wp_rewrite) || !$wp_rewrite->using_permalinks()) { return; }
    $search_base = $wp_rewrite->search_base;
    if (is_search() && !is_admin() && strpos($_SERVER['REQUEST_URI'], "/{$search_base}/") === false) {
        wp_redirect(home_url("/{$search_base}/" . urlencode(get_query_var('s'))));
        exit();
    }
}
add_action('template_redirect', 'wpa_search_redirect');

// Fix for empty search queries redirecting to home page
function wpa_request_filter($query_vars) {
    if (isset($_GET['s']) && empty($_GET['s']) && !is_admin()) {
        $query_vars['s'] = ' ';
    }
    return $query_vars;
}
add_filter('request', 'wpa_request_filter');

//  Custom AJAX search
add_filter( 'posts_search', '__search_by_title_only', 500, 2 );

function __search_by_title_only( $search, &$wp_query ){
    global $wpdb;
    if ( empty( $search ) ) return $search;
    $q = $wp_query->query_vars;
    $n = ! empty( $q['exact'] ) ? '' : '%';
    $search = $searchand = '';
    foreach ( (array) $q['search_terms'] as $term ) {
        $term = esc_sql( $wpdb->esc_like( $term ) );
        $search .= "{$searchand}($wpdb->posts.post_title LIKE '{$n}{$term}{$n}')";
        $searchand = ' AND ';
    }
    if ( !empty( $search ) ) {
        $search = " AND ({$search}) ";
        if ( ! is_user_logged_in() )
            $search .= " AND ($wpdb->posts.post_password = '') ";
    }
    return $search;
}

function cf_search_join( $join ) {
    global $wpdb;
    $join .=' LEFT JOIN '.$wpdb->postmeta. ' ON '. $wpdb->posts . '.ID = ' . $wpdb->postmeta . '.post_id ';
    return $join;
}

function cf_search_where( $where ) {
    global $pagenow, $wpdb;
    $where = preg_replace(
        "/\(\s*".$wpdb->posts.".post_title\s+LIKE\s*(\'[^\']+\')\s*\)/",
        "(".$wpdb->posts.".post_title LIKE $1) OR (".$wpdb->postmeta.".meta_value LIKE $1)", $where );
    return $where;
}

function cf_search_distinct( $where ) {
    global $wpdb;
    return "DISTINCT";
}

function wpa_ajax_search(){
    extract($_POST);
    add_filter( 'posts_join', 'cf_search_join' );
    add_filter( 'posts_where', 'cf_search_where' );
    add_filter( 'posts_distinct', 'cf_search_distinct' );
    $allsearch = new WP_Query("s=".$key."&showposts=-1&post_type=any&post_status=publish");
    if($allsearch->have_posts()): while($allsearch->have_posts()) : $allsearch->the_post();
    global $post; ?>
<p class="cfx">
    <a href="<?php the_permalink(); ?>">
        <?php if( has_post_thumbnail() ) the_post_thumbnail('thumbnail'); ?>
        <span><?php the_title(); ?></span>
    </a>
</p>
<?php endwhile; else :
    echo '<mark>There were no search results. <br />Please try using more general terms to get more results.</mark>';
    endif;
    remove_filter( 'posts_join', 'cf_search_join' );
    remove_filter( 'posts_where', 'cf_search_where' );
    remove_filter( 'posts_distinct', 'cf_search_distinct' );
    exit();
}
add_action('wp_ajax_wpa_ajax_search', 'wpa_ajax_search');
add_action('wp_ajax_nopriv_wpa_ajax_search', 'wpa_ajax_search');

search.js

//  WP AJAX Search
    $.fn.donetyping=function(n,t){t||(t=1e3);var i,u=function(t){i&&(i=null,n(t))};return this.each(function(){var n=$(this);n.on("keyup",function(){i&&clearTimeout(i),i=setTimeout(function(){u(n)},t)}).on("blur",function(){u(n)})}),this};

    $('.search_box input[type="text"]').donetyping(function(){
        var t = $('.search_box input[type="text"]'),
            val = t.val(),
            form = t.parent();
        if(val.length >= 3) {
            $.ajax({
                type: 'post',
                url: $('html').data('a'),
                data: {
                    action: 'wpa_ajax_search',
                    key: val
                },
                beforeSend: function(){
                    $('img, .close', form).fadeIn(250);
                    form.next().find('.showsearch').html('<mark>Searching...</mark>');
                },
                success: function(html) {
                    form.next().find('.showsearch').html(html);
                    $('img', form).fadeOut(250);
                }
            });
        } else {
            form.next().find('.showsearch').html('<mark>Enter 3 or more letters</mark>');
            $('img', form).fadeOut(250);
        }
    });
    $(document).on('click', '.search_box i', function(){
        $(this).fadeOut(250).prev().fadeOut(250).parent().next().find('>div').html('');
        $(this).next().val('');
    });

search.scss

.search_box {
    @include border-radius(3px);
    @include transition();
    position: relative;
    z-index: 99;
    margin: 0;
    form {
        input[type="text"] {
            @include border-radius(5px);
            padding: 0 30px 0 10px;
            border: 1px solid #ccc;
            font: 300 14px $font;
            background: #fff;
            display: block;
            width: 100%;
            height: 32px;
            margin: 0;
            color: #333;
            &:focus {
                border-color: #000
            }
        }
        button {
            @include border-radius(5px);
            position: absolute;
            background: #fff;
            cursor: pointer;
            height: 30px;
            width: 30px;
            right: 2px;
            padding: 0;
            border: 0;
            top: 1px;
            &[disabled] {
                cursor: pointer
            }
            &:before {
                @include border-radius(50%);
                border: 2px solid #333;
                @include transition();
                position: absolute;
                height: 13px;
                width: 13px;
                content: "";
                left: 5px;
                top: 5px;
            }
            &:after {
                @include transform(rotate(45deg));
                @include border-radius(3px);
                @include transition();
                position: absolute;
                background: #333;
                content: "";
                height: 2px;
                width: 10px;
                left: 18px;
                top: 21px;
            }
            &:hover {
                @include box-shadow(none);
                &:before {border-color: #16a085}
                &:after {background: #16a085}
            }
        }
        img {
            @include border-radius(5px);
            position: absolute;
            background: #fff;
            display: none;
            padding: 7px;
            z-index: 99;
            width: 30px;
            right: 1px;
            top: 1px;
        }
        .close {
            font: 400 14px/30px "Verdana",sans-serif;
            @include border-radius(5px);
            text-transform: uppercase;
            @include transition();
            text-align: center;
            position: absolute;
            background: #fff;
            cursor: pointer;
            display: none;
            height: 30px;
            width: 30px;
            z-index: 32;
            right: 1px;
            top: 1px;
            &:hover {
                color: #ef4036
            }
        }
    }
    .search_result {
        position: absolute !important;
        font: 400 14px/20px $font;
        left: 0;
        max-height: 240px;
        overflow: auto;
        right: 0;
        top: 100%;
        z-index: -1;
        .showsearch {
            padding: 7px 0 0;
            margin: -7px 0 0;
            background: #fff;
            &:empty {display: none}
        }
        mark {
            text-align: center;
            color: #707070;
            display: block;
            padding: 10px;
        }
        p {
            border-top: 1px solid #e1e1e1;
            text-align: left;
            padding: 0;
            &:first-child { border-top: 0 }
            a {
                padding: 5px 10px;
                @include flexbox();
                @include justify-content(space-around);
                @include align-items(center);
                color: #333;
                img {
                    width: 40px;
                    display: block;
                    margin: 0 10px 0 0;
                }
                span {
                    @include flex(1,0,0);
                }
                &:hover {
                    color: #707070
                }
            }
        }
    }
}

searchform.php

<div class="search_box cfx">
    <form action="<?php echo domain_name(); ?>" role="search">
        <img data-aload="<?php echo theme('images/wpa_preloader.gif'); ?>" src="<?php echo ALOAD; ?>" alt="search" />
        <i class="close">x</i>
        <input type="text" name="s" placeholder="Search..." autocomplete="off" autocapitalize="off" autocorrect="off">
        <button type="submit" class="icon-search" disabled></button>
    </form>
    <div class="search_result">
        <div class="showsearch"></div>
    </div>
</div>