term query

// WP_Term_Query arguments
$args = array(
	'taxonomy'               => array( 'category' ),
	'meta_key'               => '_primary_category',
	'meta_value'             => 'true',
	'fields'                 => 'all',
	'hide_empty'             => true,
	'get'                    => 'empty',
	'update_term_meta_cache' => true,
);

// The Term Query
$term_query = new WP_Term_Query( $args );

// The Loop
if ( ! empty( $term_query ) && ! is_wp_error( $term_query ) ) {
	// do something
} else {
	// no terms found
}