Database
db={"players_collection":[{"_id":ObjectId("5e6ffe413f71835ae3aa4b60"),"f":"Paul","id":11811,"l":"Pelè","r":64},{"_id":ObjectId("5e6ffe413f71835ae3aa4b65"),"f":"paul","id":11811,"l":"walker","r":64},{"_id":ObjectId("5e6ffe413f71835ae3aa4b66"),"f":"johnny","id":11811,"l":"Green","r":64}]}
Query
db.players_collection.find({"$or":[{"f":{"$regex":"^(Paul Green|Paul Gree|Paul|paul|pau|Gr|pele|Pel|john|joh)","$options":"i"}},{"l":{"$regex":"^(Paul Green|Paul Gree|Paul|paul|pau|Gr|pele|Pel|john|joh)","$options":"i"}},{"c":{"$regex":"^(Paul Green|Paul Gree|Paul|paul|pau|Gr|pele|Pel|john|joh)","$options":"i"}}]})