counting other units rent as income before owning?

[Athan Seyler]

I'm wanting to purchase my first rental property as being a 3plex or 4plex but I notice the mortgage may be 60%-75% of my income. i know most places would deny this but, there's some properties that'll say that there's tenants that want to stay that are providing enough rent to cover the mortgage, so is there potential for a loan officer to be more willing to provide a loan seeing that the property is already making income and will continue to (in theory). Either way I'm trying to network with those who are local to me (Portland, OR) and I will be walking into different credit unions near me to directly ask the loan officers; either way I'd appreciate different perspectives.