get_posts() and special character in meta_value

i need to use get_posts for a meta_value with a special character.

$arg = array(
            'post_status'		=> 'publish',
            'post_parent'		=> null,
            'order'			=> 'DESC',
            'orderby'			=> 'post_date',
	    'meta_value' 		=> 'südküste',
        );

How can i get the meta_value with the Umlaut ü by using get_post()?
i try to use Html entities with ü with no luck.
hope someone can help.