This kind of problems a lot of companies face but obviously there is a solution. Although, it would involve huge amount of patience and dedicated efforts but result is guaranteed.
Intensive use of LinkedIn is the best bet instead of focusing on keywords. A lot of people do use LinkedIn but their experience of generating qualified leads is not that great. I suggest you look for LinkedIn expert/Lead Gen Company who can help you to mine qualified leads which can eventually become your customers.
I am saying this based on my past experience of working with some of the top MNCs across the globe.
Should you need help, feel free to get in touch with me.