I disagree. It would be -1 for target moving and -2 for shooter moving. A target in partial cover doesn't have a penalty to hit. "PARTIAL COVER: Partial cover does not modify the hit chance, but gives you an armor level for body parts behind the cover" (PM, p65).I think in that instance it might actually be a -5 modifier, as you'd lose the +2 mod from firing at a large target. Essentially it would be a -5 against a target in partial.