Bangladesh is a country in Southern Asia. Hitching is not really understood here. However, if you are a foreigner, your mere presence will attract interest, especially outside of Dhaka. Bangladeshis are generally very helpful to foreigners, so whilst they may be amazed that you choose not to use the (very cheap) public transport, you may succeed in receiving offers of lifts.
I have not has success simply standing by the roadside. Actually, the number of private cars is very few, compared to the number of buses. I would recommend a cheery smile at a roadside cafe or petrol station.