Add ACF fields to WordPress Search

custom-acf-search.php

<?php
/**
 * [list_searcheable_acf list all the custom fields we want to include in our search query]
 * @return [array] [list of custom fields]
 */
function list_searcheable_acf(){
  $list_searcheable_acf = array("title", "sub_title", "excerpt_short", "excerpt_long", "xyz", "myACF");
  return $list_searcheable_acf;
}


/**
 * [advanced_custom_search search that encompasses ACF/advanced custom fields and taxonomies and split expression before request]
 * @param  [query-part/string]      $where    [the initial "where" part of the search query]
 * @param  [object]                 $wp_query []
 * @return [query-part/string]      $where    [the "where" part of the search query as we customized]
 */
function advanced_custom_search( $where, $wp_query ) {

    global $wpdb;
 
    if ( empty( $where ))
        return $where;
 
    // get search expression
    $terms = $wp_query->query_vars[ 's' ];
    
    // explode search expression to get search terms
    $exploded = explode( ' ', $terms );
    if( $exploded === FALSE || count( $exploded ) == 0 )
        $exploded = array( 0 => $terms );
         
    // reset search in order to rebuilt it as we whish
    $where = '';
    
    // get searcheable_acf, a list of advanced custom fields you want to search content in
    $list_searcheable_acf = list_searcheable_acf();

    foreach( $exploded as $tag ) :
        $where .= " 
          AND (
            (wp_posts.post_title LIKE '%$tag%')
            OR (wp_posts.post_content LIKE '%$tag%')
            OR EXISTS (
              SELECT * FROM {$wpdb->postmeta}
	              WHERE post_id = {$wpdb->posts}.ID
	                AND (";

        foreach ($list_searcheable_acf as $searcheable_acf) :
          if ($searcheable_acf == $list_searcheable_acf[0]):
            $where .= " (meta_key LIKE '%" . $searcheable_acf . "%' AND meta_value LIKE '%$tag%') ";
          else :
            $where .= " OR (meta_key LIKE '%" . $searcheable_acf . "%' AND meta_value LIKE '%$tag%') ";
          endif;
        endforeach;

	        $where .= ")
            )
            OR EXISTS (
              SELECT * FROM {$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 = {$wpdb->term_taxonomy}.term_taxonomy_id
              WHERE (
          		taxonomy = 'post_tag'
            		OR taxonomy = 'category'          		
            		OR taxonomy = 'myCustomTax'
          		)
              	AND object_id = {$wpdb->posts}.ID
              	AND wp_terms.name LIKE '%$tag%'
            )
        )";
    endforeach;
    return $where;
}
 
add_filter( 'posts_search', 'advanced_custom_search', 500, 2 );