Applying singapore PR?

Hi, im malaysian. im already work in Singapore for 5 years. currenty holding work permit. im just resign from my previous company 3 month ago with salary $1800 permonth (5 years working). now, im working with other company for 3 months with salary $1500 and after confirm up to $1600. am i eligible for applying PR? and what kind of doent that i need to submit?FYI, my current company is willing to support my application to applying PR if im eligble. The probs is this company is just operate for 4 mnths. pls help