$cat = get_terms('job_listing_category');
$cat_array = array();

foreach($cat as $cat){

    if($value == $cat->slug)
    {
        $cat_array[] = $cat->slug;
    }


}
$meta_query = ('tax_query' => array(
array(
  'taxonomy' => 'job_listing_category',
  'field'    => 'slug',
  'terms'    => $cat_array
),