I think minimum also wear a polo t with jeans or cargo pants and covered shoes. No matter the weather is hot and humid. Don't wear bermudas with sandals and show your hairy legs. Looks like you are going downstairs market to buy a packet of Char Kway Teow! Be more professional and show respect to your client's big day of their life. You are a hired photographer for goodness sake. Especially at the wedding dinner. If you dress with bermudas or shorts in sandals I think the hotel waiter waitress or the cleaner auntie uncle also dress better than you. If you look well dressed and professional the chances of you getting business from your client's friend and relatives are also higher.