part time job

Not sure about your status in Singapore (citizen, PR or work pass holder). If you are a citizen or PR then you may look for part time job. If holding work pass then not entitled to apply second job.

If you are coming here as a visitor and looking for a part time then it’s illegal to work while you are on visa. Though you may do illegally but if caught, you will be deported with fine and may be black listed in ICA record. So, choice is yours.

Actually i'm not citizen. I come from Indonesia and i was a student and i want spend my holiday to looking for job in Singapore. There is any advice for me? Thanks for your information

Forget about part time jobs - they are not allowed for foreigners. Also, you cannot work at all while here on a visitor (tourist) visa.
If you want to work in Singapore, look for a full-time job, let the employer apply for a regular work pass (WP, S-Pass or EP, depending on your education, work experience and salary). Then start work after the work pass is issued - not before!