Common-law spouses of Overseas Networks & Expertise Pass holders can work in Singapore with a Letter of Consent.
The prospective employer of a common-law spouse of an Overseas Networks & Expertise Pass holder must submit an application to MOM for a Letter of Consent on their behalf.
Other Long-Term Visit Pass holders who are not common-law spouses will need to obtain a work pass to work in Singapore.
You first need to get a job offer in Singapore, then get your prospective employer to apply for an Employment Pass, S Pass or Work Permit for you. You will have to meet all the criteria for the pass that your employer is applying for.