How to add search field to the Find Invoices form in Payables

My Customer needs to be able to search by Cost Center segment in the Find Invoices form in Payables. I see that it´s possible to search by Project and Task for example and also PO information but it does not seem to be possible to search for COA key flexfield segments (Balancing, Cost Center, Natural Accont). Is there some inqury form in Payables that I don´t know of where it´s possible to search for invoices based on key flexfield values, for example Cost Center value?

Or is it advisable to customize the Find Invoices form.

Thanks

Arny