JAVASCRIPT

mongoose search in multiple fields

let regex = new RegExp(value.searchQuery,'i');
const filterd = await Model.find({ $and: [ { $or: [{title: regex },{description: regex}] }, {category: value.category}, {city:value.city} ] })

Mongoose search multiple fields

var re = new RegExp(req.params.search, 'i');

app.User.find().or([{ 'firstName': { $regex: re }}, { 'lastName': { $regex: re }}]).sort('title', 1).exec(function(err, users) {
    res.json(JSON.stringify(users));
});