Ajax搜索，如何将taxemony post_tag添加到数组中？

I have an ajax search where i output results from categories from a custom post type called "portfolio". I have registered a post_tag taxonomy for this custom post typ, and want to include post_tag in the search. I tried taxonomy => 'post_tag', but no luck. Ideally i would like the post_tag to show with the page titel, not the category. This is the array: (full code: http://pastebin.com/3BruDsL0)

if (!function_exists('sf_ajaxsearch')) {
    function sf_ajaxsearch() {
        $search_term = trim($_POST['s']);
        $search_query_args = array(
            's'                 => $search_term,
            'post_type'         => 'any',
            'portfolio-category'=> 'fullvids,indie,feed',
            'post_status'       => 'publish',
            'suppress_filters'  => false,
            'numberposts'       => -1
        );
    }
}