I doubt that you will attain any "happy" feelings from fentanyl, it's a very cold drug, most do not consider it to be recreational. It's a fully synthetic, extremely potent opioid narcotic, active in the microgram range, used for treatment of chronic pain and also for general anesthesia and analgesia in a hospital environment or other controlled setting where vital signs including oxygen levels in the blood are monitored to prevent fatal respiratory depression, for which fentanyl is infamous.
Do not tamper with the patch, fentanyl is not a drug do be abused. I've abused it, it's no fun, it's not worth it. I am not even the kind of person who thinks they're only good for staving off withdrawals, I think that's still abuse of the patch, any use other than for legitimate pain is abuse and is not safe by any stretch of the imagination.
Do not mix fentanyl with any CNS depressants including but not limited to alcohol, benzodiazepines, other opioids such as oxycodone, etc.
While a tolerance of 150mg oxycodone per day (equal to ~225mg morphine PO) comes out to around the equivalent of a 75mcg/hour patch, that's by no mean a green light to slap on the 25mcg/hour, it's not worth betting your life on, we are not doctors, I just used an online opioid converter.
Personally, I would rather go sick than use a fentanyl patch.