As far as I am aware, you have two options:
1. I've heard IBM has started selling an integrated package of PC and z/OS, which is the only legal way right now to get z/OS on a small machine. I have heard that the price starts at 20,000 U.S. dollars (at least here in the U.S.) and you could not run it on your laptop -- you must use the machine IBM provides.
2. Hercules is an open-source emulation of 360/370/... architecture that can be downloaded and installed on almost any machine. Early versions of MVS (say 20 to 30 years old) were not copyrighted and can be installed and run on Hercules. I have heard that people have gotten z/OS running on Hercules, but that is a violation of the license for z?OS and if discovered by IBM could result in anything from the organization losing its license to run z/OS to a lawsuit.
You might be able to find somewhere to rent time on their mainframe, in which case your laptop would be running a 3270 emulator connecting to the mainframe. Renting time isn't generally cheap (I've heard 200 to 1000 U.S. dollars per month), your laptop would only be able to do mainframe activities while connected, and there may be usage charges to raise the monthly cost.