To fillup required field's value on any button press event

In Openerp when we have required fields in any object-form so first we need to fill up that field's value to click on any buttons which are in that object form.

Suppose, In sales order form customer, ordering contact, invoice address, shipping address etc. are required fields and we want to fill up that field's value by other object's data using 'Get Information' named button so what we need to do now first need to fill up all the required field's value and then need to click on that 'Get Information' named button which will fill up that field's value according to our logic which we wrote in that button's action so it is not good way to do like that.

so can its possible that we can pass arguments in XML for 'button' tag and mention fields name for which button press event ignore to check that field's value is already fill up OR not and we can perform button's action without that trace. I know that its possible by on_change event for any object field and using it we can fill up other field's value but if there is a requirement that when we press button then and then only other field's value fill up as our button action logic, specially for case to fill up required field's value.