Better use the findOne query. It is faster than find.
You said fields, so let's suppose that means name, email, and username.
Now, if you want to check if the value lets say, "hashnode" is present in any of these,
you simply go for,
User.findOne({
$or: [
{ name: "hashnode" },
{ email: "hashnode"},
{ username: "hashnode" }
]
}).exec()