You are mentioning Personas as well as Target Audience in the same breath, but they are slightly different.
Target Audience (used by marketing in order to separate customers into dedicated groups for selling effort)
- are mainly distinguished by demographics
- sometimes with income
- sometimes with behaviours and lifestyle too
Personas (used by software development in order to separate groups of users for tailoring the interface)
- are distinguished by demographics
- show behaviours and attitutes
- and most important, they describe goals these users have
JonW already told in his comment your target audience. If you are unsure, if these clients are Personas too - they are not, because they are not using the software!
I would treat them as (external) stakeholders in your software development process. That means, they have interests in the software and possibly some specific needs. But these needs go into feature gathering rather than decisions how the interface concept is made, because they will not use it by themself.