global $query_string;

$query_args = explode("&", $query_string);
$search_query = array();

foreach($query_args as $key => $string) {
	$query_split = explode("=", $string);
	$search_query[$query_split[0]] = urldecode($query_split[1]);
} // foreach

$all = get_posts(array('post_type'=> 'page', 'posts_per_page' => -1));
    $parents = array();
    foreach ($all as $single)
    {
        $kids = get_children($single->ID);  
        if(isset($kids) && !empty($kids) && count($kids) >= 1)
        {
            $parents[] = $single->ID;
        }
    }

$search_query['post__in'] = $parents;
$search = new WP_Query($search_query);