Where will your clents be travelling to I wonder? This year the bayram falls over 4 days from the 27th November.

In Istanbul where I live, the day before the holiday is very busy and all the shops are open. Over the next 4 days some shops will close for a couple of days and some will have limited opening. Having said that, the main shopping centres such as Cevahir will be open for business as normal.

Public transport still runs though can be pretty crowded as over the holiday its generally free to use.

Overall your clents wont encounter any restrictions. I hope they enjoy their stay