function keyLookup(obj, string) {
    if (_.isObject(obj)) {
        var path = null;
        _.find(obj, function(value, key) {
            if (_.isString(key) && key.includes(string)) {
                path = key.toString();
                return true;
            } else if (_.isObject(value) && !_.isFunction(value)) {
                var foundKeyValueRec = keyLookup(value, string);
                // Call recursively
                if (foundKeyValueRec) {
                    path = key + ' : ' + foundKeyValueRec;
                    return true;
                }
            }
        });
        return path;
    }
}

// Test:

var testObj = {
    someStuff: 1,
    someObjectStuff: {
        arr: [1, 2, 3]
    },
    a: {
        b: {
            func : function() {
                return 1;
            },
            c: [
                {
                    test : {
                        f : 1
                    }
                },
                1
            ]
        }
    }
}

keyLookup(testObj, "test") // returns "a : b : c : 0 : test"