i had the same problem, for my new site i just added a new meta "title" :

#functions.php
    
    add_action('save_post', 'title_to_meta');
    
    function title_to_meta($post_id)
    {
    	update_post_meta($post_id, 'title', get_the_title($post_id)); 
    }

And then.. just add something like that :

    $sub = array('relation' => 'OR');
    
    $sub[] = array(
    	'key'     => 'tags',
    	'value'   => $_POST['q'],
    	'compare' => 'LIKE',
    );
    
    $sub[] = array(
    	'key'     => 'description',
    	'value'   => $_POST['q'],
    	'compare' => 'LIKE',
    );
    
    $sub[] = array(
    	'key'     => 'title',
    	'value'   => $_POST['q'],
    	'compare' => 'LIKE',
    );
    
    $params['meta_query'] = $sub;

What do you think about this workaround ?