$args = array(
        'post_type' => 'job-vacancies',
        'posts_per_page' => -1,
        'order' => 'ASC',
    );

    if (isset($_POST['region_select']) && isset($_POST['job_cat'])) {
        $args['tax_query'] = array(
            array(
                'taxonomy' => 'jobs',
                'field' => 'id',
                'terms' => $_POST['job_cat']
            ),
            array(
                'taxonomy' => 'region',
                'field' => 'id',
                'terms' => $_POST['region_select']
            )
        );
    }


    if (isset($_POST['region_select']) == '' || isset($_POST['job_cat'])) {
        $args['tax_query'] = array(
            array(
                'taxonomy' => 'jobs',
                'field' => 'id',
                'terms' => $_POST['job_cat']
            )
        );
    }

    if (isset($_POST['region_select']) || isset($_POST['job_cat']) == '') {
        $args['tax_query'] = array(
            array(
                'taxonomy' => 'region',
                'field' => 'id',
                'terms' => $_POST['region_select']
            )
        );
    }