Using a Bluetooth receiver with 3.5mm jack headset
I've been using Sony SBH20 for this purpose. You can try this one also (attach a small power bank for powering the device).


The first one is small in size but it might be difficult to interface with the adjustment controls. Whereas the second one is a little big but the adjustment controls are better. 
Apart from the above factors both can be connected to your existing headphones and have quit a similar feature set.
Unfortunately, the answer to your question is too broad &amp; with just a google search you will have the ability to choose from a lot of product options then the ones mentioned here.
You need to do a search for Bluetooth receiver. Most of the results would be something like a USB dongle but a few results should match your needs.