Query Toolset with custom post category

$args = array(
	'post_type' => 'custom_post_type',
	'posts_per_page' => 1,
	'meta_key' => 'wpcf-custom-slug',
  'orderby' => 'meta_value_num',
  'order' => 'DESC',
  'tax_query' => array(
		array(
			'taxonomy' => 'custom-category',
			'field' => 'slug',
			'terms' => 'custom-term-slug',
		)
	)
);