Have your client contact the employer to request a hard copy.  If they were not filed, are final paystubs for the year still available? (or an abstract from the final payroll register from the year)

Contacting the IRS Practioner Priority Service will not procur the Wage & Income Transcript documents because (1) the W2s were not filed with SSA and (2) IRS is in process of purging certain back years ..... so a Wage and Income Transcript from PPS will  not provide information. {Note that the aforementioned transcript would not contain state withholdings if your goal is to also file state returns for the year in question}.