Graphic designer for ongoing work relationship

We are looking to build an on-going relationship with a designer that could even perhaps look to dedicate a few days per week for various projects, across our different client accounts. Work would include design and artwork production across various media, both online and offline. To start with we would look at an hourly rate to see if we 'fit' and then if all runs smoothly would consider a monthly retainer for an agreed amount of days per month. We react quickly to our clients, so clear communication with us is key to manage client expectation and deliver on our promises. We have high standards and always go above and beyond, so someone with the same mindset would fit well.