Database
[{"key":1,"userName":"John-den","userCode":{"userName":"John-den","description":{"userName":"John-den"}}}]
Query
db.collection.update({},[{"$set":{"userName":{"$replaceAll":{"input":"$userName","find":"John","replacement":"Naruto"}},"userCode.userName":{"$replaceAll":{"input":"$userName","find":"John","replacement":"Naruto"}},"userCode.description.userName":{"$replaceAll":{"input":"$userName","find":"John","replacement":"Naruto"}}}}],{multi:true})