WordPress Admin Post Search extend to one custom field


I would like to extend the WordPress admin post search (so in back-end) in order to look at keywords in post title but also in one custom field.

I find this thread interesseting (except the custom post type because I don’t use it) : Extending the search context in the admin list post screen and adapt my function like below :

function rel_search_join( $  join ) {     global $  pagenow, $  wpdb;     if ( is_admin() && $  pagenow == 'edit.php' && $  _GET['post_type'] == 'post' && $  _GET['s'] != '') {             $  join .= 'LEFT JOIN ' . $  wpdb->postmeta . ' ON '. $  wpdb->posts . '.ID = ' . $  wpdb->postmeta . '.post_id ';     }     return $  join; } add_filter('posts_join', 'rel_search_join' );  function rel_search_where( $  where ) {     global $  pagenow, $  wpdb;     if ( is_admin() && $  pagenow == 'edit.php' && $  _GET['post_type']=='post' && $  _GET['s'] != '' ) {         $  where = preg_replace( "/\(\s*".$  wpdb->posts.".post_title\s+LIKE\s*(\'[^\']+\')\s*\)/", "(".$  wpdb->posts.".post_title LIKE $  1) OR (".$  wpdb->postmeta.".my-custom-field-meta-key LIKE $  1)", $  where );         $  where = str_replace( "OR wp_posts.post_status = 'pending'", "", $  where );         $  where = str_replace( "OR wp_posts.post_status = 'private'", "", $  where );         $  where = str_replace( "OR wp_posts.post_status = 'draft'", "", $  where );         $  where = str_replace( "OR wp_posts.post_status = 'future'", "", $  where );     }     return $  where; } add_filter( 'posts_where', 'rel_search_where' ); 

But this does not work at all, the search was no longer working at all.

I feel like there is a way easier solution but I am not able to find it on any forums.

I know there are other solutions like custom field filters but it is not suitable for my custom field which can have thousands of values.

PS : I use Advanced Custom Field but I don’t think there is any connection.