SQL 2012 :: How To Do Dynamic Audit For The Tables

I would like to do a dynamic audit for the tables ( columns which needs to audited will also change dynamically). For example,

I am having 3 tables, table1 table2 table3

User can select Table 1 ( col 1, col3, col4) and Table2 ( col 3 and col 5).

I want to achieve this functionality without any triggers or output clause, so only one option which is left is "ChangeDataCapture" ( to my knowledge). So i did a small POC. The problem here is, system captures all the field data even though value doesn't change, for example,

TableA

CountryId CountryCode CountryName
1 IND INDIA
Update TableA
Set CountryCode = 'INDI', CountryName = 'INDIA'
Where CountryId = 1

On running the above query, CDC stores the value for both the columns, but i don't want this. I only wanted to store the CountryCode value alone.

CREATE TABLE [dbo].tCountry(
CountryId bigint IDENTITY(1,1) NOT NULL Primary Key,
CountryName [varchar](50) NULL,
CountryCode [varchar](50) NULL,
CreateBy bigint
)
EXEC sys.sp_cdc_enable_db

[code]....

--See here, i want to display CountryName as NULL, because i didnt do any changes in this column

--Why am i asking this bcoz, Frm my front end application, i will send the complete list of columns and the values to the update query.

Select * from cdc.dbo_tCountry_CT Where __$operation in (3,4)