"oppa please pat my head" "pat" corresponds to "토닥이다" in Korean. So you can translate it as "오빠 내 머리 좀 토닥여줘". The sentence doesn't seem to sound all that natural though. Also, 토닥이다 is usually used for patting on the back or shoulder, not on the head. On the head, 쓰다듬다 (caress) is much more common.