Without any further details about the business, P/L, burnrate/runway, ... in case you have for your product (which is about to be completed and ready to ship in 1-3 months) "some valuable partnerships" - ask your prospective (or already signed) customers for an order without shipping the product, but paying it in parts or full. Explain them your situation, be clear and precise in your wording. You obviously have to show them some of your numbers and have to negotiate future contractual benefits - paying back the gratitude. Maybe when you can rally up some, you get the short-term liquidity to make the next milestone. The whole approach is risky, bc if one customer doesn't show up, the parade will not play music.
Or (2) you could got to a specialised bank like http://www.svb.com/, pitch them, and ask for a debt/equity round. They are always looking for customers. Tell them you got this tip from here. I read from time to time their blog. And they have a Europe location too, as it isn't obvious where you are, your business is located.
(3) Sand Hill Road. VC companies who have a portfolio comparable to your product, early-stage focused. Could take your more than 2 or 3 months.
