Match exact search term including tax/terms

functions.php

add_filter( 'posts_search', 'my_search_is_perfect', 20, 2 );

function my_search_is_perfect( $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( like_escape( $term ) );

        $search .= "{$searchand}(
             $wpdb->posts.post_title REGEXP '[[::]]')
             OR ($wpdb->posts.post_content REGEXP '[[::]]')
             OR ((SELECT COUNT(wp_terms.term_id) FROM wp_term_relationships
             LEFT JOIN wp_term_taxonomy ON wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id
             LEFT JOIN wp_terms ON wp_term_taxonomy.term_id = wp_terms.term_id
             WHERE (wp_term_relationships.object_id = $wpdb->posts.ID)
             AND (wp_terms.name REGEXP '[[::]]')) > 0)
           ";
        $searchand = ' AND ';
    }

    if ( ! empty( $search ) ) {
        $search = " AND ({$search}) ";
        if ( ! is_user_logged_in() )
            $search .= " AND ($wpdb->posts.post_password = '') ";
    }

    return $search;
}