Add tags to wordpress search

wp-tags-to-search.php

<?php
// ADD Tags To SEARCH
function my_smart_search( $search, &$wp_query ) {
    global $wpdb;
 
    if ( empty( $search ))
        return $search;
 
    $terms = $wp_query->query_vars[ 's' ];
    $exploded = explode( ' ', $terms );
    if( $exploded === FALSE || count( $exploded ) == 0 )
        $exploded = array( 0 => $terms );
         
    $search = '';
    foreach( $exploded as $tag ) {
        $search .= " AND (
            ($wpdb->posts.post_title LIKE '%$tag%')
            OR ($wpdb->posts.post_content LIKE '%$tag%')
            OR EXISTS
            (
                SELECT * FROM $wpdb->comments
                WHERE comment_post_ID = $wpdb->posts.ID
                    AND comment_content LIKE '%$tag%'
            )
            OR EXISTS
            (
                SELECT * FROM $wpdb->terms
                INNER JOIN $wpdb->term_taxonomy
                    ON $wpdb->term_taxonomy.term_id = $wpdb->terms.term_id
                INNER JOIN $wpdb->term_relationships
                    ON $wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id
                WHERE taxonomy = 'post_tag'
                    AND object_id = $wpdb->posts.ID
                    AND $wpdb->terms.name LIKE '%$tag%'
            )
        )";
    }
 
    return $search;
}
 
add_filter( 'posts_search', 'my_smart_search', 500, 2 );

?>