Updating key of an object

[Ashish Kumar]

Which function can i use if i want to update a field inside an object ?

For Example:
{
"day": "2017-01-27",
"clicks": {
"50,100": 1,
"100,150": 3
}
}
This is a document..how can i increment the value of "50,100" key ?

Any kind of help is appreciated.