Front-end ordering and ordering by custom field

Hi all,

I'd like to add the ability for users to change the ordering of a category listing upon a custom field.

From what I can see there is no way of doing so without modifying the 'components/com_flexicontent/models/category.php' file.

I managed to edit this file to implement an additional query string "orderby=xxx"; however I'm not too sure how I reference a non-core field.

For example, the default ordering by 'title' is referenced 'i.title' in the order part of the query.

I'm trying to order by a custom field called 'client' and using 'client' or 'i.client' in the query returns errors.

So, my questions are:

> How do I reference my custom field called client in the order part of the query.

> Is there a better way to implement this?

> I couldnt find anything but is there already an extension for FLexiContent that provides this?

Thanks in advance for any guidance,
Kris...