Order Portfolio Items by Custom field?

Is there any way to order portfolio items using a custom field?
I have added a custom field using the advanced custom fields plugin.
The field is called ‘orientation’ and has options of portrait or landscape.
I would like to order the portfolio items using this field in order images of a similar orientation are grouped together.
I am happy to add the functoinality a different way if needs be.
(it would be even better if I coudl order first by the Orientation and then by Post Title, but the orientation is the most important)
Thanks in advance