Partial views are more a template for either a control or a set of controls that can be shared between views.
I'm not sure they are "Custom Controls" as such and it sounds like you are coming from an ASP viewpoint.
I think you need to first get in the mindset of MVC and out of ASP.
So for a list of items you may have a partial view that takes the list of items and a partial view that takes an actual item. So "pvCustomerList<List<customer>>" and "pvCustomer<customer>".
The pcCustomerList iterates through the list and creates a pvCustomer for each customer in the list.
Partial Views don't really have code in the controller. Instead they are passed data from the view. If there is a submit action in the partial view, then this is either handled by the controller for the view or a jQuery post back.
I hope this clears things up a little for you.
Have you checked out NerdDinner sample?