This will go in taxnonomy.php or taxonomy-name.php templates.

$term = get_term_by( 'slug', get_query_var('term'), get_query_var('taxonomy') ); 

$customField = get_field('custom_field_name')];
$args = array(
	'posts_per_page' => '-1',
	'post_type' 	 => 'service_centres',
	'tax_query' => array (
		array (
			'taxonomy' => 'regions',
			'field' => 'slug',
			'terms' =>  $term->slug
		)
	),
	'meta_key'	 => 'custom_field_name',
	'meta_value'	 => 'custom_field_value_value'
);