How to pass form Key fields to a custom form

Using javascript, I'm opening a  custom RQ10 in a new window and want to pass the Key fields (i.e. Requester, Requisition Number) to RQ10 in the new window. Also, would like RQ10 to "Inquire" automatically with the form key fields (Requester, Requistion Number).

I've got the javascript to open a new window with custom RQ10 but there are no Key fields.

Anybody done this before?