Have nodejs module use files defined in the directory of the caller

I am defining a Nodejs module, config.js, which will have all the logic to read the configuration file written in json.

I want to use this module else where in a different node module and have it use the configuration file defined in this different node module.

for eg:

var Config = require('config')

Config.getPoroperty('client.url')

Here the actual json file which has client.url defined in it, would be defined in the directory structure of the module where the Config module is used. The logic to read this json file is defined in config module

How do i achieve that?