Database
[{"_id":{"$oid":"65fc6b08a0ffe6dd598b114f"},"userId":{"KEY1":["1","2","3"],"KEY2":["A","Z"]}},{"_id":{"$oid":"22fc6b11a0ff111d598b114a"},"userId":{"KEY1":["4","5","6"],"KEY2":["Z","X"]}},{"_id":{"$oid":"22fc6b11a0ff111d598b114b"},"userId":{"KEY1":["0","8","9"],"KEY2":["F","P"]}}]
Query
db.collection.find({$or:[{"userId.KEY1":{$in:["2","X"]}},{"userId.KEY2":{$in:["2","X"]}}]})