WW2 bomber downed on the territory of former Yugoslavia

I'm looking for the information about downed USA bomber of WW2 on the territory of the former Yugoslavia (now Bosnia and Herzegovina). I know it was a mission of bombing oil refinery in Ploesti, Romania and I assume it was B24 Liberator. The crew was rescued by Tito's partisans. I even have a photo of the crew with the local population. It was from the summer 1943. And I even have a part of the plane that my late grandfather brought home from the crash site.
I would like to contact one of the descendants of the crew members or donate this part of the plane to one of the American museums.