Since you indicate that you expect the part rolled over to the Roth IRA to be taxable, I assume that there is nothing in box 5 of this Form 1099-R. If there is nothing in box 5, the details of this Form 1099-R imply that you instructed the plan to do a direct rollover of the entire amount to a traditional IRA but somehow you diverted some of the funds to a Roth IRA instead. (Either that or the plan issued a Form 1099-R with an incorrect taxable amount in box 2a.) This means that the Form 1099-R does not reflect the rollovers that actually occurred.
Whether or not there is anything in box 5, to accommodate TurboTax you'll need to split the Form 1099-R into two, one for the portion rolled over to the traditional IRA and another for the portion rolled over to the Roth IRA. For the portion rolled over to the Roth IRA you'll need to put the taxable amount in box 2a; with a zero in box 2a TurboTax will treat the portion rolled over to the Roth IRA as nontaxable. Because the split Forms 1099-R will not sum to the total in box 2a of the original, these probably should be done as substitute Forms 1099-R (Forms 4852).
