Issue in customizing label for each element in Column Stacked Chart

[avanti]

stacked column chart.pngI
I have above column stacked chart component in my application. In the label as shown in the screenshot above, I want the label to be populated using store data field name and value like Metric1 15% where Metric1 is field name and 15% is data value. Right now it is hardcoded. Using renderer function just gives data value.
Please let me know how can I pass field name to the renderer function alongwith data value.

[mitchellsimoens]

The renderer passes the record for each, it should be the 2nd argument